1. Field of the Invention
The present invention relates to a process and an apparatus for supplying solid feed materials for a direct smelting process to solids injection lances of a direct smelting vessel.
2. Description of Related Art
A known direct smelting process that is generally referred to as the HIsmelt process is described in International Application PCT/AU96/00197 (WO96/31627) and in other patent applications in the name of the applicant.
The following discussion of the HIsmelt process is not to be taken as an admission of common general knowledge.
The HIsmelt process includes the steps of:                (a) forming a molten bath of iron and slag in a vessel;        (b) injecting into the bath:                    (i) an iron-containing feed material, typically iron ore or partially reduced iron ore; and            (ii) a solid carbonaceous material, typically coal, which acts as a reductant of the iron-containing feed material and a source of energy; and                        (c) smelting iron-containing feed material to iron in the bath.        
The term “smelting” is herein understood to mean thermal processing wherein chemical reactions that reduce iron-containing material take place to produce molten iron.
The iron-containing feed material and the solid carbonaceous material are injected into the molten bath through a number of solids injection lances which are inclined to the vertical so as to extend downwardly and inwardly through the side wall of the vessel and into the lower region of the vessel so as to deliver the solids materials deep into the molten bath.
The HIsmelt process also includes post-combusting reaction gases, such as CO and H2, that are released from the bath into a space above the bath with oxygen-containing gas and transferring the heat generated by post-combustion to the bath to contribute to the thermal energy required to smelt iron-containing feed material.
Typically, the oxygen-containing gas is a blast of hot air, which may be oxygen enriched, that is injected into an upper region of the vessel through a downwardly extending hot air injection lance. Offgases resulting from post-combustion of reaction gases in the vessel are taken away from an upper part of the vessel through an offgas duct.
The HIsmelt process enables large quantities of molten iron to be produced by direct smelting in a single compact vessel.
However, in order to achieve this it is necessary to supply large quantities of solid feed materials, namely iron-containing feed material, carbonaceous material, and fluxes, to the solids injection lances.
The supply of solid feed materials must continue throughout a smelting campaign, which desirably is at least 12 months.
Moreover, it must be possible to vary the supply of solid feed materials during the course of a smelting campaign to accommodate different operating conditions, including unexpected perturbations in the process, at different stages of a smelting campaign.